Filtering noise values from telemetry data

ABSTRACT

In an embodiment, a data processing method providing an improvement in filtering telemetry data received from mobile devices comprises receiving, from a mobile device, telemetry data comprising a plurality of probes, each probe identifying a location of the mobile device at a time of the probe, wherein the plurality of probes form first digital trace data identifying a path of the mobile device; determining, for a particular probe of the plurality of probes, a first attribute of the particular probe; determining whether the first attribute of the particular probe satisfies a first threshold; in response to satisfying the first threshold, deleting the particular probe from the plurality of probes and dividing the first digital trace data into second digital trace data and third digital trace data; performing an action using the second digital trace data and the third digital trace data.

TECHNICAL FIELD

The technical field of the present disclosure generally relates toimproved methods, computer software and/or computer hardware in thefield of electronic maps. The disclosure relates more specifically toimproved computer-implemented methods for filtering noise from telemetrydata.

BACKGROUND

The approaches described in this section could be pursued, but are notnecessarily approaches that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, the approaches describedin this section are not prior art to the claims in this application andare not admitted to be prior art by inclusion in this section.

Digitally stored electronic maps are used to provide directions to usersof mobile devices, for example, using any of a wide array of standalonemap or direction application programs or apps. Today's electronic mapscorrectly determine where a mobile device is within a few feet ormeters, or show where the user of that mobile device is on theelectronic map in real time. Electronic maps also typically includeother functionality, such as providing turn-by-turn directions to nearlyany location. Additional elements such as traffic or wrecks may also beshown.

Electronic maps also appear in other applications aside from standalonemapping applications. For example, ride sharing applications, taxiapplications, video games, and other applications may use digital maps.These or other applications can obtain electronic maps by calling a mapserver computer through an Application Programming Interface (API).Thus, a single electronic map provider that owns or operates the servercomputer may supply the electronic maps for many different applications.

When a mobile device is using an electronic map, the location of themobile device can be determined using WiFi or the Global PositioningSystem (GPS), which reports a device location using latitude andlongitude, and optionally height and time as well. This location data,as well as other data, may be collected by the electronic map providerand may be termed “telemetry” data for the mobile device. However, theremay be noise or errors in the collected data. GPS drift or reflection ofGPS signals from buildings, geographic features or other obstructionsmay result in incorrect reports. Depending on the type of device used toreport location, the telemetry data that is collected may be noisy. Infact, many mobile devices report data that is so noisy that it isunusable at the collecting computer. This severely limits the potentialuses of telemetry data from mobile computing devices. Thus, improvedmethods of filtering noise from telemetry data are needed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates an example computer system in which the techniquesdescribed may be practiced, according to one embodiment.

FIG. 2 illustrates a programmable algorithm or method in accordance withan embodiment.

FIG. 3A and FIG. 3B graphically illustrate an example implementation offiltering noise from telemetry data.

FIG. 4 illustrates a computer system upon which an embodiment may beimplemented.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be apparent, however,that the present invention may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring thepresent invention. Embodiments are described in sections according tothe following outline:

-   1. Overview-   2. Example Computer System Implementation-   3. Example Functional Implementation-   4. Example Filtering of Noise from Telemetry Data-   5. Hardware Overview

1. Overview

Computer-implemented techniques are provided for filtering noise fromtelemetry data. “Noise,” in this context, may be reported real-worldlocation data that does not accurately identify the true geographicposition of a mobile computing device due to one or more of a variety offactors. Example causes of noise include, but are not limited to:reflection from tall buildings or geographic features or other sources,varying quality levels of GPS receivers in mobile devices, varying powerlevels of GPS receivers in mobile devices, other physical limitations ofmobile devices, and user or application imposed limitations in GPSaccuracy. Additional source of noise may be incorrectly configuredmobile computing devices, which can result in telemetry data from thefuture if the date/time is incorrect on the mobile computing device.

In various embodiments, telemetry data is received from mobile computingdevices. The telemetry data includes many values of probes. Each probeis a report consisting of a plurality of data values identifying alocation of the mobile computing device at the time of the report. Eachof the probes may include values for latitude, longitude, time, and/orheight, for example. A plurality of probes from a single mobilecomputing device, when considered together, may form a tracerepresenting a path of movement of the mobile computing device.Obtaining a trace is of particular use when the mobile computing deviceis traveling in a vehicle, such as a bicycle, car, or train. The mobilecomputing devices may be many different types of physical devices, asdiscussed below, although the mobile computing devices are typicallysmartphones.

Telemetry data received from mobile computing devices may have one ormore instances of poor quality data. In an embodiment, a plurality ofindividual probes that form a trace are examined. In one approach, for agiven probe value, additional attributes for the probe are determined orcalculated using one or more other probe values that were receivedimmediately before or after the given probe, or both. The probesimmediately before or after a given probe may not be used if, forexample, the probes immediately before or after are determined to be baddata. If the probes immediately before or after contain bad telemetrydata, then the next or prior good probe, or both, may be used.Alternatively, any configuration of good probes or telemetry data may beused to determine the additional attributes. Example additionalattributes include, but are not limited to: speed, acceleration,deceleration, trajectory change, distance, or duration. Each attributeis compared to a corresponding stored threshold value, and adetermination is made whether the threshold is satisfied.

For example, a speed threshold value may be 90 miles per hour. For thisthreshold value, if a given probe and one or more other probe valuesindicate a speed of motion in excess of 90 miles per hour, then thethreshold is satisfied and the given probe may represent noise. While 90miles per hour may be the true speed of a vehicle that is carrying amobile computing device, it may indicate noise if analysis of sets ofimmediately earlier and later probes indicates speeds that are muchlower. The foregoing is merely one example of a heuristic that can beimplemented in computer-executed steps to identify noise in probe data.

In one embodiment, if the threshold value is satisfied, then the givenprobe is deleted, and the trace is then split or divided into twotraces. This is repeated for each probe. In some cases, a tracerepresenting a complete trip of a mobile computing device from astarting point to a destination may be split into many different traces.

The traces resulting from this process may also be filtered using, forexample, a minimum number of probes as a threshold. The resulting tracesmay be stored, optionally using anonymization to enforce privacy rules,and may be used by a variety of applications or algorithms.Alternatively, the traces may have been anonymized prior to beginningthe process described herein.

In one embodiment, a data processing method providing an improvement infiltering telemetry data received from mobile devices comprisesreceiving, from a mobile device, telemetry data comprising a pluralityof probes, each probe identifying a location of the mobile device at atime of the probe, wherein the plurality of probes form a first digitaltrace data identifying a path of the mobile device; determining, for aparticular probe of the plurality of probes, a first attribute of theparticular probe; determining whether the first attribute of theparticular probe satisfies a first threshold; in response to satisfyingthe first threshold, deleting the particular probe from the plurality ofprobes and dividing the first digital trace data into a second digitaltrace data and a third digital trace data; performing an action usingthe second digital trace data and the third digital trace data.

Other embodiments, aspects and features will become apparent from thedisclosure as a whole.

2. Example Computer System Implementation

FIG. 1 illustrates an example computer system in which the techniquesdescribed may be practiced, according to one embodiment.

In an embodiment, a computer system 100 comprises components that areimplemented at least partially by hardware at one or more computingdevices, such as one or more hardware processors executing storedprogram instructions stored in one or more memories for performing thefunctions that are described herein. In other words, all functionsdescribed herein are intended to indicate operations that are performedusing programming in a special-purpose computer or general-purposecomputer, in various embodiments. FIG. 1 illustrates only one of manypossible arrangements of components configured to execute theprogramming described herein. Other arrangements may include fewer ordifferent components, and the division of work between the componentsmay vary depending on the arrangement.

FIG. 1 illustrates a mobile computing device 145 that is coupled via awireless network connection 165 to a server computer 105, which iscoupled to a database 120. A GPS satellite is coupled via a wirelessconnection to the mobile computing device 145. The server computer 105comprises a mapping application 110, an application programminginterface (API) 112, noise filtering instructions 115 and a databaseinterface 117. The database 120 comprises electronic map source data125, electronic map data 130, telemetry data 135, aggregated telemetrydata 140 and trace data 142. The mobile computing device 145 comprises aGPS transceiver 150, client map application 155, software developmentkit (SDK) 157 and wireless network interface 159.

Server computer 105 may be any computing device, including but notlimited to: servers, racks, work stations, personal computers, generalpurpose computers, laptops, Internet appliances, wireless devices, wireddevices, multi-processor systems, mini-computers, and the like. AlthoughFIG. 1 shows a single element, the server computer 105 broadlyrepresents one or multiple server computers, such as a server cluster,and the server computer may be located in one or more physicallocations. Server computer 105 also may represent one or more virtualcomputing instances that execute using one or more computers in adatacenter such as a virtual server farm.

Server computer 105 is communicatively connected to database 120 andmobile computing device 145 through any kind of computer network usingany combination of wired and wireless communication, including, but notlimited to: a Local Area Network (LAN), a Wide Area Network (WAN), oneor more internetworks such as the public Internet, or a company network.Server computer 105 may host or execute mapping application 110, and mayinclude other applications, software, and other executable instructions,such as database interface 117, to facilitate various aspects ofembodiments described herein.

In one embodiment, database interface 117 is a programmatic interfacesuch as JDBC or ODBC for communicating with database 120. Databaseinterface 117 may communicate with any number of databases and any typeof database, in any format. Database interface 117 may be a piece ofcustom software created by an entity associated with mapping application110, or may be created by a third party entity in part or in whole.

In one embodiment, database 120 is a data storage subsystem consistingof programs and data that is stored on any suitable storage device suchas one or more hard disk drives, memories, or any other electronicdigital data recording device configured to store data. Althoughdatabase 120 is depicted as a single device in FIG. 1, database 120 mayspan multiple devices located in one or more physical locations. Forexample, database 120 may include one or nodes located at one or moredata warehouses. Additionally, in one embodiment, database 120 may belocated on the same device or devices as server computer 105.Alternatively, database 120 may be located on a separate device ordevices from server computer 105.

Database 120 may be in any format, such as a relational database, anoSQL database, or any other format. Database 120 is communicativelyconnected with server computer 105 through any kind of computer networkusing any combination of wired and wireless communication of the typepreviously described. Optionally, database 120 may be communicativelyconnected with other components, either directly or indirectly, such asone or more third party data suppliers. Generally, database 120 storesdata related to electronic maps including, but not limited to:electronic map source data 125, electronic map data 130, telemetry data135, aggregated telemetry data 140, and trace data 142. These datasetsmay be stored as columnar data in a relational database or as flatfiles.

In one embodiment, electronic map source data 125 is raw digital mapdata that is obtained, downloaded or received from a variety of sources.The raw digital map data may include satellite images, digital streetdata, building or place data or terrain data. Example sources includeNational Aeronautics and Space Administration (NASA), United StatesGeological Survey (USGS), and DigitalGlobe. Electronic map source data125 may be updated at any suitable interval, and may be stored for anyamount of time. Once obtained or received, electronic map source data125 is used to generate electronic map data 130.

In one embodiment, electronic map data 130 is digital map data that isprovided, either directly or indirectly, to client map applications,such as client map application 155, using an API. Electronic map data130 is based on electronic map source data 125. Specifically, electronicmap source data 125 is processed and organized as a plurality of vectortiles which may be subject to style data to impose different displaystyles. Electronic map data 130 may be updated at any suitable interval,and may include additional information beyond that derived fromelectronic map source data 125. For example, using aggregated telemetrydata 140, discussed below, various additional information may be storedin the vector tiles, such as traffic patterns, turn restrictions,detours, common or popular routes, speed limits, new streets, and anyother information related to electronic maps or the use of electronicmaps.

In one embodiment, telemetry data 135 is digital data that is obtainedor received from mobile computing devices via function calls that areincluded in a Software Development Kit (SDK) that application developersuse to integrate and include electronic maps in applications. Asindicated by the dotted lines, telemetry data 135 may be transientlystored, and is processed as discussed below before storage as aggregatedtelemetry data 140.

The telemetry data may include mobile device location information basedon GPS signals. For example, telemetry data 135 may comprise one or moredigitally stored events, in which each event comprises a plurality ofevent attribute values. Telemetry events may include: session start, mapload, map pan, map zoom, map tilt or rotate, location report, speed andheading report, or a visit event including dwell time plus location.Telemetry event attributes may include latitude-longitude (latlong)values for the then-current position of the mobile device, a sessionidentifier, instance identifier, application identifier, device data,connectivity data, view data, and timestamp.

In one embodiment, aggregated telemetry data 140 is telemetry data 135that has been processed using anonymization, chunking, filtering, or acombination thereof. Anonymization may include removing any data thatidentifies a specific mobile device or person. Chunking may includesegmenting a continuous set of related telemetry data into differentsegments or chunks representing portions of travel along a route. Forexample, telemetry data may be collected during a drive from John'shouse to John's office. Chunking may break that continuous set oftelemetry data into multiple chunks so that, rather than consisting ofone continuous trace, John's trip may be from John's house to point A, aseparate trip from point A to point B, and another separate trip frompoint B to John's office. Chunking may also remove or obscure startpoints, end points, or otherwise break telemetry data into any size.Filtering may remove inconsistent or irregular data, delete traces ortrips that lack sufficient data points, or exclude any type or portionof data for any reason. Once processed, aggregated telemetry data 140 isstored in association with one or more tiles related to electronic mapdata 130. Aggregated telemetry data 140 may be stored for any amount oftime, such as a day, a week, or more. Aggregated telemetry data 140 maybe further processed or used by various applications or functions asneeded.

In one embodiment, trace data 142 is a set of aggregated telemetry datathat represents the movement of a mobile device from a first point to asecond point. A particular trace may contain two or more GPS datapoints, or probes, depending on the length of the trace and howfrequently GPS data was provided from an associated mobile computingdevice. As a result of the processes described herein, or otherprocesses, a particular trace data item does not necessarily correlateto a complete real-world movement of an associated mobile device. Tracedata 142 may be stored for any amount of time. Trace data 142 is aresult of filtering telemetry data 135 or aggregated telemetry data 140.

In one embodiment, mobile computing device 145 is any mobile computingdevice, such as a laptop computer, hand-held computer, wearablecomputer, cellular or mobile phone, portable digital assistant (PDAs),GPS or other dongle, any portable navigation device, or tablet computer.Additionally or alternatively, mobile computing device 145 is anavigation system installed in a car or other vehicle. Although a singlemobile computing device is depicted in FIG. 1, any number of mobilecomputing devices may be present. Each mobile computing device 145 iscommunicatively connected to server computer 105 through wirelessnetwork connection 165 which comprises any combination of a LAN, a WAN,one or more internetworks such as the public Internet, a cellularnetwork, or a company network.

Mobile computing device 145 is communicatively coupled to GPS satellite160 using GPS transceiver 150. GPS transceiver 150 is a transceiver usedby mobile computing device 145 to receive signals from GPS satellite160, which broadly represents three or more satellites from which themobile computing device may receive signals for resolution into alatitude-longitude position via triangulation calculations.

Mobile computing device 145 also includes wireless network interface 159which is used by the mobile computing device to communicate wirelesslywith other devices. In particular, wireless network interface 159 isused to establish wireless network connection 165 to server computer105. Wireless network interface 159 may use WiFi, WiMAX, Bluetooth,ZigBee, cellular standards or others.

Mobile computing device 145 also includes other hardware elements, suchas one or more input devices, memory, processors, and the like, whichare not depicted in FIG. 1. Mobile computing device 145 also includesapplications, software, and other executable instructions to facilitatevarious aspects of embodiments described herein. These applications,software, and other executable instructions may be installed by a user,owner, manufacturer, or other entity related to mobile computing device.In one embodiment, mobile computing device 145 includes client mapapplication 155 which is software that displays, uses, supports, orotherwise provides electronic mapping functionality as part of theapplication or software. Client map application 155 may be any type ofapplication, such as a taxi service, a video game, a chat client, a fooddelivery application, etc. In an embodiment, client map application 155obtains electronic mapping functions through SDK 157, which mayimplement functional calls, callbacks, methods or other programmaticmeans for contacting the server computer to obtain digital map tiles,layer data, or other data that can form the basis of visually renderinga map as part of the application. In general, SDK 157 is a softwaredevelopment kit that allows developers to implement electronic mappingwithout having to design all of the components from scratch. Forexample, SDK 157 may be downloaded from the Internet by developers, andsubsequently incorporated into an application which is later used byindividual users.

In server computer 105, the mapping application 110 provides the API 112that may be accessed, for example, by client map application 155 usingSDK 157 to provide electronic mapping to client map application 155.Specifically, mapping application 110 comprises program instructionsthat are programmed or configured to perform a variety of backendfunctions needed for electronic mapping including, but not limited to:sending electronic map data to mobile computing devices, receivingtelemetry data 135 from mobile computing devices, processing telemetrydata to generate aggregated telemetry data 140, generating trace data142, organizing trace data 142, receiving electronic map source data 125from data providers, processing electronic map source data 125 togenerate electronic map data 130, and any other aspects of embodimentsdescribed herein. Mapping application 110 includes noise filteringinstructions 115 which are programmed or configured to filter noise fromtelemetry data. Specifically, noise filtering instructions 15 may filternoise from telemetry data 135, aggregated telemetry data 140, or tracedata 142.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to perform identifying prior and subsequent probes for agiven probe of a trace. The prior and subsequent probes may beidentified based upon earlier or later time values. For example, theprobes may be ordered according to the time value of the probe, and theprior and subsequent probes identified based on the time values.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to determine attributes of a probe. The attributes may bedetermined using the given probe, a prior probe, a subsequent probe, ora combination thereof, and using one or more probe values at thosepoints, in various embodiments. Attributes may include, but are notlimited to: speed, acceleration, deceleration, trajectory change,distance, and a duration value. Speed indicates the speed of the mobilecomputing device at the time of the probe. Acceleration indicates a rateof acceleration of the mobile computing device at the time of the probe.Deceleration indicates a rate of deceleration of the mobile device atthe time of the probe. Trajectory change indicates how much of a changein the direction of travel there has been relative to the prior probe,the subsequent probe, or both. Distance indicates how far apart theprobe is from prior or subsequent probes, or both. Duration indicateshow much time has passed since a prior probe, until a subsequent probe,or both. Any number of attributes may be determined. The number ofattributes determined may vary based on a use of the data afterfiltering. In one embodiment, attributes may be determined without usinga prior or subsequent probe. For example, attributes may be determinedbased on data of the given probe, such as a time or date. If the time ordate is incorrect or invalid, then the probe likely contains low qualitytelemetry data.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to perform setting thresholds for attributes. Each attributemay have a different threshold, and the thresholds may vary based on theuse of the data after filtering. The thresholds may be set based onspecific values, such as 100 miles per hour or 15 seconds.Alternatively, the thresholds may be set based on a percentage, arelative amount or any other standard. Depending on the attribute, thethreshold may be satisfied by exceeding the threshold, or by failing tomeet the threshold.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to perform determinations of whether attributes of a probesatisfy thresholds. The determinations may be made in a predeterminedorder, such as beginning with the threshold which is most commonlysatisfied and ending with the least commonly satisfied threshold, or inany other order. The determination is made for each probe in a trace.The determination that a threshold is satisfied may be made in anysuitable manner. When a threshold is satisfied, the associated probe islikely noise, and will be deleted as discussed below. If a threshold isnot satisfied, then the associated probe may not be noise, and is notdeleted.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to delete probes in response to satisfying thresholds andsplitting traces into multiple traces. Satisfying a single thresholdindicates that the probe is likely noise and thus should be deleted. Theprobes may be deleted by erasing it from digital memory or storage usinga write or update operation.

When a probe is deleted, in an embodiment, rather than interpolatingdata for the probe, the trace is divided into two or more new traces.For example, if a trace contains 256 probes having identifier valuesfrom 0 to 255, and probe number 48 is determined to be noise, then thetrace would be split into two traces, with the first trace containingprobe numbers 0 to 47, and the second trace containing probe numbers 49to 255. Dividing may comprise writing one set of probe values to a newstorage location, changing identifier values, creating or updatingpointer values or other references, or other techniques. The identifiervalues and probe numbers given in this example are hypothetical, andother values may be used in various embodiments. The dividing of tracesinto multiple traces may be performed directly after a deletion, or maybe performed at a subsequent point, such as after all probes in aparticular trace have been filtered or processed.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to store trace data. The new traces resulting from divisionoperations are stored in memory, a flat file, a database or otherelectronic digital storage medium.

Once stored, the trace data may be used in a variety of applications. Inparticular, due to the quality of the resulting trace data, and becausethe trace data was not matched or otherwise linked to an electronic mapprior to filtering, the trace data may be used to improve electronicmaps, among other applications or uses.

In one embodiment, noise filtering instructions 115 are programmed orconfigured to perform filtering of traces. The traces may be filteredusing a threshold count or amount of probes. In other words, if a tracedoes not contain a specified minimum number of probes, the trace isdeleted. The threshold may be any amount, such as four probes. Inparticular, the filtering of traces is used when one trace has beensplit into many traces, as some of the newly created traces may containinsufficient probes to be accurate or useful. Alternatively, the tracesmay be filtered using any other basis, for any other reason, or at anytime.

3. Example Functional Implementation

FIG. 2 illustrates an example programmable algorithm or method forfiltering noise from telemetry data. Although the steps in FIG. 2 areshown in an order, the steps of FIG. 2 may be performed in any order,and are not limited to the order shown in FIG. 2. Additionally, somesteps may be optional, may be performed multiple times, and/or may beperformed by different components. All steps, operations and functionsof a flow diagram that are described herein are intended to indicateoperations that are performed using programming in a special-purposecomputer or general-purpose computer, in various embodiments, at thesame level of detail that is used by persons of ordinary skill in theart to which the disclosure pertains for communicating with one anotherabout similar computer programs or algorithms. In other words, each flowdiagram in this disclosure is a guide, plan or specification of analgorithm for programming a computer to execute the functions that aredescribed.

In step 200, telemetry data is received from mobile computing devices.As indicated by the dotted lines, the telemetry data may be receivedbefore the method of FIG. 2 begins, while the method of FIG. 2 isperformed, or at any other time. The telemetry data may be received fromany number of mobile computing devices, and may contain any suitableinformation. Typically, the telemetry data is received in the form ofprobes, which identify a location of a mobile computing device at thetime of the probe. When considered together, multiple probes from asingle mobile computing device form a trace, which represents the pathof a mobile computing device over a period of time. For example, a tracemay represent a trip from a workplace to a restaurant.

In step 205, the probes of a particular trace are identified. Any numberof probes may be identified in a particular trace, and the probes may beidentified in any suitable manner. In particular, for a given probe, theprior and the subsequent probe are identified for use in subsequentsteps. Optionally, multiple prior and subsequent probes may beidentified, such as 2 prior and 3 subsequent, or any other amount ofprior and subsequent probes.

In step 210, the attributes of a probe are determined. The attributes ofa probe are determined using zero or more prior probes, subsequentprobes, or any combination thereof. In one embodiment, the prior probeand the subsequent probe, or a combination thereof, may be used.Alternatively, the attributes may be determined using additional probesor different probes than the prior probe, the subsequent probe, or both.For example, a probe that is two probes before the particular probe anda probe that is three probes after the particular probe may be used, orany other combination. Which probes are used in determining theattributes may be based on any suitable factors, such as whether theprobes contain good or bad telemetry data. As an example, no prior orsubsequent probes may be used when the attribute is based on a timevalue, and the current probe contains a date or time from the future,and therefore clearly incorrect. Attributes of a probe include, but arenot limited to: a speed value, an acceleration value, a decelerationvalue, a trajectory change value, distance, or a duration value. Anynumber of attributes may be determined for a probe. Each attribute hasan associated threshold. The thresholds may be set to any suitableamount by any entity. The thresholds may vary by attribute, may varybased on an application or intended use of the telemetry data, or mayvary based on any other reason. Typically, the thresholds are set suchthat noisy, inaccurate or faulty probes are identified and removed, asdiscussed below.

In step 215, a determination is made whether any attribute satisfies acorresponding threshold. If any attribute does satisfy a threshold, themethod proceeds to step 220. If no thresholds are satisfied, the methodproceeds to step 225. Satisfying even a single threshold indicates thatthe probe is likely inaccurate or otherwise is low quality, and resultsin the method proceeding to step 220. Thus, even if a probe has eightattributes, and only a single one of the eight satisfies a threshold,the method still proceeds to step 220.

In step 220, the probe is deleted. The probe may be deleted in anymanner. By deleting the probe, the quality of the telemetry data isincreased, and allows for more complicated and demanding calculations oractions to be performed using the telemetry data.

In step 225, a determination is made whether there are additional probesin the trace. The determination may be made in any way. If there areadditional probes, the method proceeds to step 230. If there are notadditional probes, the method proceeds to step 235.

In step 230, the method moves to the next probe in the trace, andreturns to step 210 to determine the attributes of the next probe.

In step 235, the trace data is divided into multiple traces based ondeleted probes. A single trace representing a complete trip betweenendpoints or destinations may be split into any number of new traces,depending on how many probes were deleted from the complete trace. Forexample, if a trace originally contains 30 probes, and probes 5, 15, and20 are deleted, then the trace will be split into 4 traces that containoriginal probes 1 to 4, 6 to 14, 16 to 19, and 21 to 30, respectively.Optionally, step 235 may be performed at a different time, such asdirectly after the deletion of a probe, or at any other time.

In step 240, the traces are filtered. As indicated by the dotted line,step 240 is optional, and may not be performed or may be performed at adifferent time than the location shown in FIG. 2. The traces may befiltered based on any attribute, feature, or other aspect. Specifically,since some traces may have been split into multiple traces, the tracesmay be filtered based on a number of probes the traces contain. Thethreshold amount of probes may be set to any amount, such as 0, 2, 4, 7,or any other number of probes. If the trace does not have the minimumnumber of probes, the trace and the associated probes are deleted.

In step 245, the traces are stored. The traces may be stored in adatabase or any other suitable electronic digital storage medium. Thetraces may be stored for any amount of time. In one embodiment, thetraces are not stored individually. Rather, the traces are aggregatedfor use in various types of actions or analysis, and the individualtraces are subsequently deleted.

In step 250, a determination is made whether there is additionaltelemetry data to filter. If there is additional telemetry data, a nexttrace is selected and the method returns to step 205 to identify theprobes of the next trace. If there is not additional telemetry data, themethod proceeds to step 255.

In step 255, actions are performed using the traces or aggregated tracedata. Many different actions may be performed with the trace data, suchas determining improvements to electronic maps such as identifying lanesof roads, identifying turn restrictions, identifying new roads,determining traffic patterns, sending a notification, performinganalytics or other analysis, or any other action. The actions performedusing the traces or aggregated trace data may influence the thresholdsor filter parameters described above. For example, determining the speedof traffic requires highly accurate speed data and thus requires strictthresholds and filters. Conversely, determining a missing street doesnot require highly accurate speed data, and thus would require lessstrict thresholds and filters.

Using this process, previously unusable telemetry data from mobilecomputing devices may be made useable. Rather than discarding traces orprobes that represent noise, the methods herein result in creating andstoring more accurate data and building larger sets of usable data. Themethod disclosed herein may improve the quality of telemetry datareceived from mobile computing devices so that the filtered telemetrydata is approximately the quality expected from high-accuracy computingdevices. The disclosed methods provide useful benefits because thequantity of telemetry data available from mobile computing devices islarge, and previously was unusable for many actions or analysis thatrequires high quality telemetry data. By increasing the quality of thetelemetry data, new actions or analysis may be performed using the largeamount of telemetry data available from mobile computing devices.Consequently, the techniques herein can permit processing data withfewer CPU cycles because server computers and other processors are notrequired to execute error routines when noisy or erroneous data isencountered.

4. Example Filtering of Noise from Telemetry Data

FIG. 3A and FIG. 3B illustrate an example of filtering noise fromtelemetry data in accordance with an embodiment.

In the embodiment of FIG. 3A, telemetry data has been received from amobile computing device. The telemetry data is shown as trace 300, whichincludes a variety of probes. The probes are connected with lines to aidin more clearly illustrating the example. Trace 300 represents themovement of a mobile computing device as the user of the mobilecomputing device rides in a car along straight road. Trace 300 showsthat the car sped up and slowed down a few times, as shown by thevariable distances between probes, and includes probe D 320, which is anoisy or inaccurate probe, as the location of probe D 320 was influencedby GPS drift. The process of filtering probe D 320 from trace 300 isdiscussed in detail below.

Specifically, trace 300 includes probe A 305, probe B 310, probe C 315,probe D 320, probe E 325, probe F 330, and probe G 335. In the processof filtering trace 300, attributes are determined for each probe,beginning with probe A 305, and continuing until the end of trace 300 atprobe G 335. As discussed above, the attributes may be anythingincluding speed, acceleration, deceleration, trajectory change,distance, or duration. For this example, the attributes of probe D 320are of interest.

When determining the attributes of probe D 320, the prior probe, probe C315, and the subsequent probe, probe E 325, may be used. The attributesof probe D 320 include a large amount of acceleration and a high speed,as probe D 320 has drifted and the location is incorrect. When thethresholds for acceleration or speed are checked against theacceleration or speed of probe D 320, the threshold is satisfied, thusindicating that probe D 320 is noisy and should be deleted. FIG. 3Bshows the deletion of probe D 320.

In the embodiment of FIG. 3B, probe D 320 of FIG. 3A has been deleted.Subsequently, two new traces have been created, trace A 340 and trace B345. In other words, trace 300 of FIG. 3A has been split into trace A340 and trace B 345. Trace A 340 includes probe A 305, probe B 310, andprobe C 315, while trace B 345 includes probe E 325, probe F 330, andprobe G 335.

5. Hardware Overview

According to one embodiment, the techniques described herein areimplemented by one or more special-purpose computing devices. Thespecial-purpose computing devices may be hard-wired to perform thetechniques, or may include digital electronic devices such as one ormore application-specific integrated circuits (ASICs) or fieldprogrammable gate arrays (FPGAs) that are persistently programmed toperform the techniques, or may include one or more general purposehardware processors programmed to perform the techniques pursuant toprogram instructions in firmware, memory, other storage, or acombination. Such special-purpose computing devices may also combinecustom hard-wired logic, ASICs, or FPGAs with custom programming toaccomplish the techniques. The special-purpose computing devices may bedesktop computer systems, portable computer systems, handheld devices,networking devices or any other device that incorporates hard-wired andprogram logic to implement the techniques.

For example, FIG. 4 is a block diagram that illustrates a computersystem 400 upon which an embodiment of the invention may be implemented.Computer system 400 includes a bus 402 or other communication mechanismfor communicating information, and a hardware processor 404 coupled withbus 402 for processing information. Hardware processor 404 may be, forexample, a general purpose microprocessor.

Computer system 400 also includes a main memory 406, such as a randomaccess memory (RAM) or other dynamic storage device, coupled to bus 402for storing information and instructions to be executed by processor404. Main memory 406 also may be used for storing temporary variables orother intermediate information during execution of instructions to beexecuted by processor 404. Such instructions, when stored innon-transitory storage media accessible to processor 404, rendercomputer system 400 into a special-purpose machine that is customized toperform the operations specified in the instructions.

Computer system 400 further includes a read only memory (ROM) 408 orother static storage device coupled to bus 402 for storing staticinformation and instructions for processor 404. A storage device 410,such as a magnetic disk or optical disk, is provided and coupled to bus402 for storing information and instructions.

Computer system 400 may be coupled via bus 402 to a display 412, such asa cathode ray tube (CRT), for displaying information to a computer user.An input device 414, including alphanumeric and other keys, is coupledto bus 402 for communicating information and command selections toprocessor 404. Another type of user input device is cursor control 416,such as a mouse, a trackball, or cursor direction keys for communicatingdirection information and command selections to processor 404 and forcontrolling cursor movement on display 412. This input device typicallyhas two degrees of freedom in two axes, a first axis (e.g., x) and asecond axis (e.g., y), that allows the device to specify positions in aplane.

Computer system 400 may implement the techniques described herein usingcustomized hard-wired logic, one or more ASICs or FPGAs, firmware andprogram logic which in combination with the computer system causes orprograms computer system 400 to be a special-purpose machine. Accordingto one embodiment, the techniques herein are performed by computersystem 400 in response to processor 404 executing one or more sequencesof one or more instructions contained in main memory 406. Suchinstructions may be read into main memory 406 from another storagemedium, such as storage device 410. Execution of the sequences ofinstructions contained in main memory 406 causes processor 404 toperform the process steps described herein. In alternative embodiments,hard-wired circuitry may be used in place of or in combination withsoftware instructions.

The term “storage media” as used herein refers to any non-transitorymedia that store data and instructions that cause a machine to operationin a specific fashion. Such storage media may comprise non-volatilemedia and volatile media. Non-volatile media includes, for example,optical or magnetic disks, such as storage device 410. Volatile mediaincludes dynamic memory, such as main memory 406. Common forms ofstorage media include, for example, a floppy disk, a flexible disk, harddisk, solid state drive, magnetic tape, or any other magnetic datastorage medium, a CD-ROM, any other optical data storage medium, anyphysical medium with patterns of holes, a RAM, a PROM, and EPROM, aFLASH-EPROM, NVRAM, any other memory chip or cartridge.

Storage media is distinct from but may be used in conjunction withtransmission media. Transmission media participates in transferringinformation between storage media. For example, transmission mediaincludes coaxial cables, copper wire and fiber optics, including thewires that comprise bus 402. Transmission media can also take the formof acoustic or light waves, such as those generated during radio-waveand infra-red data communications.

Various forms of media may be involved in carrying one or more sequencesof one or more instructions to processor 404 for execution. For example,the instructions may initially be carried on a magnetic disk or solidstate drive of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over atelephone line using a modem. A modem local to computer system 400 canreceive the data on the telephone line and use an infra-red transmitterto convert the data to an infra-red signal. An infra-red detector canreceive the data carried in the infra-red signal and appropriatecircuitry can place the data on bus 402. Bus 402 carries the data tomain memory 406, from which processor 404 retrieves and executes theinstructions. The instructions received by main memory 406 mayoptionally be stored on storage device 410 either before or afterexecution by processor 404.

Computer system 400 also includes a communication interface 418 coupledto bus 402. Communication interface 418 provides a two-way datacommunication coupling to a network link 420 that is connected to alocal network 422. For example, communication interface 418 may be anintegrated services digital network (ISDN) card, cable modem, satellitemodem, or a modem to provide a data communication connection to acorresponding type of telephone line. As another example, communicationinterface 418 may be a local area network (LAN) card to provide a datacommunication connection to a compatible LAN. Wireless links may also beimplemented. In any such implementation, communication interface 418sends and receives electrical, electromagnetic or optical signals thatcarry digital data streams representing various types of information.

Network link 420 typically provides data communication through one ormore networks to other data devices. For example, network link 420 mayprovide a connection through local network 422 to a host computer 424 orto data equipment operated by an Internet Service Provider (ISP) 426.ISP 426 in turn provides data communication services through the worldwide packet data communication network now commonly referred to as the“Internet” 428. Local network 422 and Internet 428 both use electrical,electromagnetic or optical signals that carry digital data streams. Thesignals through the various networks and the signals on network link 420and through communication interface 418, which carry the digital data toand from computer system 400, are example forms of transmission media.

Computer system 400 can send messages and receive data, includingprogram code, through the network(s), network link 420 and communicationinterface 418. In the Internet example, a server 430 might transmit arequested code for an application program through Internet 428, ISP 426,local network 422 and communication interface 418.

The received code may be executed by processor 404 as it is received,and stored in storage device 410, or other non-volatile storage forlater execution.

Extensions and Alternatives

In the foregoing specification, embodiments of the invention have beendescribed with reference to numerous specific details that may vary fromimplementation to implementation. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense. The sole and exclusive indicator of the scope of the invention,and what is intended by the applicants to be the scope of the invention,is the literal and equivalent scope of the set of claims that issue fromthis application, in the specific form in which such claims issue,including any subsequent correction.

What is claimed is:
 1. A data processing method for filtering noise fromtelemetry data received from a mobile device of a plurality of mobiledevices, the method comprising: receiving, from the mobile device, thetelemetry data comprising a plurality of probes, each probe of theplurality of probes identifying a location of the mobile device at atime of said each probe, wherein the plurality of probes forms a firstdigital trace identifying a path of the mobile device and comprises aseries of probes of the plurality of probes that begins with a firstprobe, ends with a last probe, and includes a particular probe;determining, for the particular probe of the plurality of probes, avalue for a first attribute of a plurality of attributes of theparticular probe from the received telemetry data; determining a firststored threshold value for the first attribute above which correspondsto a noise value for the first attribute; comparing the determinedparticular probe value for the first attribute for the particular probeto the first stored threshold value for the first attribute; in responseto the determined particular probe value for the first attributeexceeding the first stored threshold: deleting the particular probe fromthe plurality of probes; and creating, from the series of probesremaining in the first digital trace, a second digital trace and a thirddigital trace, wherein the second digital trace begins with the firstprobe and ends with a second probe immediately preceding the particularprobe in the series of probes, and the third digital trace begins with athird probe immediately following the particular probe in the series ofprobes and ends with the last probe; storing the second digital traceand the third digital trace, wherein the first stored threshold variesbased on an action to be taken using the second digital trace and thethird digital trace; and determining whether the second digital trace orthe third digital trace satisfy a third threshold for a minimum numberof probes of the plurality of probes; in response to the second digitaltrace or the third digital trace not satisfying the third threshold,deleting the second digital trace or the third digital trace.
 2. Themethod of claim 1, further comprising: determining, for the particularprobe, a second attribute of the particular probe; determining whetherthe second attribute of the particular probe satisfies a secondthreshold; deleting the particular probe in response to the firstattribute satisfying the first threshold or the second attributesatisfying the second threshold.
 3. The method of claim 1, wherein thefirst attribute is: a speed value, an acceleration value, a decelerationvalue, a trajectory change value, a distance value, or a duration value.4. The method of claim 1, wherein the mobile device is a smartphone. 5.The method of claim 1, wherein the first attribute is determined usingat least a prior probe or a subsequent probe, wherein the second digitaltrace data ends on the prior probe, and wherein the third digital tracedata begins on the subsequent probe.
 6. The method of claim 1, whereinthe received telemetry data has not been matched to an electronic map.7. The method of claim 1, wherein the action comprises improving anelectronic map.
 8. The method of claim 1, further comprising: performingthe method of claim 1 for a plurality of telemetry data received from aplurality of mobile devices.
 9. A system comprising: a database; one ormore servers communicatively connected to the database, the one or moreservers comprising one or more processors and electronic digital memorystoring one or more sequences of instructions which, when executed bythe one or more processors, cause the one or more processors to perform:receiving, from a mobile device, telemetry data comprising a pluralityof probes, each probe identifying a location of the mobile device at atime of said each probe, wherein the plurality of probes forms a firstdigital trace identifying a path of the mobile device and comprises aseries of probes of the plurality of probes that begins with a firstprobe, ends with a last probe, and includes a particular probe;determining, for the particular probe of the plurality of probes, avalue for a first attribute of a plurality of attributes of theparticular probe from the received telemetry data; determining a firststored threshold value for the first attribute above which correspondsto a noise value for the first attribute; comparing the determinedparticular probe value for the first attribute for the particular probeto the first stored threshold value for the first attribute; in responseto the determined particular probe value for the first attributeexceeding the first threshold: deleting the particular probe from theplurality of probes; and creating, from the series of probes of theplurality of probes remaining in the first digital trace, a seconddigital trace and a third digital trace, wherein the second digitaltrace begins with the first probe and ends with a second probeimmediately preceding the particular probe in the series of probes, andthe third digital trace begins with a third probe immediately followingthe particular probe in the series of probes and ends with the lastprobe; storing the second digital trace and the third digital trace,wherein the first threshold varies based on an action to be taken usingthe second digital trace and the third digital trace; and determiningwhether the second digital trace or the third digital trace satisfy athird threshold for a minimum number of probes of the plurality ofprobes; in response to the second digital trace or the third digitaltrace not satisfying the third threshold, deleting the second digitaltrace or the third digital trace.
 10. The system of claim 9, theinstructions further causing the one or more processors to perform:determining, for the particular probe, a second attribute of theparticular probe; determining whether the second attribute of theparticular probe satisfies a second threshold; deleting the particularprobe in response to the first attribute satisfying the first thresholdor the second attribute satisfying the second threshold.
 11. The systemof claim 9, wherein the first attribute is: a speed value, anacceleration value, a deceleration value, a trajectory change value, adistance value, or a duration value.
 12. The system of claim 9, whereinthe mobile device is a smartphone.
 13. The system of claim 9, whereinthe first attribute is determined using at least a prior probe or asubsequent probe, wherein the second digital trace ends on the priorprobe, and wherein the third digital trace begins on the subsequentprobe.
 14. The system of claim 9, wherein the received telemetry datahas not been matched to an electronic map.
 15. The system of claim 9,wherein the action comprises improving an electronic map.
 16. The systemof claim 9, the instructions further causing the one or more processorsto perform: performing the steps of claim 9 for a plurality of telemetrydata received from a plurality of mobile devices.